The presence of phenols in various hydrocarbonaceous streams is troublesome. For example, the presence of phenols in liquids produced from coal causes instability of these liquids over a period of time by increasing the viscosity, the color intensity, and causing the separation of resinous materials. Moreover, without extensive hydrotreatment, coal liquids are generally not compatible with petroleum liquids of comparable boiling point. Thus, solids separation caused largely by high concentrations of phenols, leads to severe operability problems for coal/petroleum liquid blends. Furthermore, hydrodesulfurization and hydrodenitrogenation of coal liquids are required prior to reforming into motor gasoline. These steps would require a relatively large consumption of hydrogen for the phenol-rich coal liquids because of the extensive deoxygenation of phenols to water.
Various methods for removing these troublesome phenols from hydrocarbonaceous streams are taught in the art. For example, it is taught in U.K. Pat. No. 494,450 that weakly acid-reacting organic substances such as phenols, can be separated from hydrocarbonaceous streams by use of alkali metal or alkaline-earth metal oxides or hydroxides in the presence of an auxiliary agent such as an aliphatic polar compound. It is taught in U.S. Pat. No. 4,256,568, which is incorporated herein by reference, that phenols react with these oxides and hydroxides resulting in the formation of metal phenates, which are easily separated from the purified stream. Further, it is taught in Ges. Abhandl. Kenninis Kohle, Vol. 4, pp. 237-63 (1919), that certain metal phenates, such as calcium phenoxide, can be heated in the presence of carbon dioxide to yield phenols and calcium carbonate.
Still another method for separating such phenols is taught in U.S. Pat. No. 4,256,568, which method comprises treating a phenol-containing stream, such as a coal liquid, with a multivalent metal oxide and/or hydroxide. The resulting hydroxy metal phenate is then pyrolyzed to a temperature of about 650.degree. C. to recover the phenols and an oxide of the multivalent metal.
Another method is disclosed in U.S. Pat. No. 4,299,691 which also employs a multivalent metal oxide and/or hydroxide for removal of phenols from phenol-containing hydrocarbonaceous streams. The resulting hydroxy metal phenates are then reacted with one or more C.sub.1 to C.sub.10 aliphatic alcohols or C.sub.7 to C.sub.16 arylalkyl primary alcohols.
Although some of these methods are commercially feasible in various industries, there is still a need to develop a process for removing, from hydrocarbonaceous streams, troublesome phenols and recovering the phenols and a metal hydroxide in a more efficient and inexpensive way.